K

Ksp

Ksp = [M^n+]^a[X^m-]^b
Quick Reference
Formula / NotationKsp = [M^n+]^a[X^m-]^b
Also Known AsSolubility product, solubility product constant, Ksp constant, solubility equilibrium constant

What is Ksp?

Ksp is the solubility product constant — the equilibrium constant for the dissolution of a sparingly soluble ionic compound. For a salt MₐXᵦ dissolving in water: MₐXᵦ(s) ⇌ aM^n+(aq) + bX^m−(aq), the Ksp = [M^n+]^a × [X^m−]^b. A larger Ksp indicates greater solubility. Ksp is used to predict precipitation and to calculate the maximum concentration of ions before precipitation occurs.

Formula & Notation

Ksp = [M^n+]^a[X^m-]^b

Other Names / Synonyms: Solubility product, solubility product constant, Ksp constant, solubility equilibrium constant

Properties & Characteristics

Ksp expression excludes solid (activity = 1). Temperature dependent. AgCl: Ksp = 1.8×10⁻¹⁰. BaSO₄: Ksp = 1.1×10⁻¹⁰. CaCO₃: Ksp = 3.4×10⁻⁹. PbS: Ksp = 8×10⁻²⁸. Common ion effect: adding same ion decreases solubility. pH effect on salts of weak acids.

Uses & Applications

Predicting precipitation in analytical chemistry. Water treatment (removing heavy metals). Qualitative analysis (precipitating specific ions). Understanding mineral dissolution in geology. Pharmaceuticals (solubility of drug salts). Dental chemistry (tooth enamel dissolution: hydroxyapatite Ksp). Environmental chemistry.

Safety Information

Calculation tool — safety depends on ions involved. Heavy metal precipitation (Pb²⁺, Hg²⁺, Cd²⁺) involves toxic substances. Precipitation of toxic metal sulfides generates H₂S. Handle precipitating agents appropriately.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Ksp
Formula Ksp = [M^n+]^a[X^m-]^b
Synonyms Solubility product, solubility product constant, Ksp constant, solubility equilibrium constant

Frequently Asked Questions

Ksp is the solubility product constant — the equilibrium constant for the dissolution of a sparingly soluble ionic compound. For a salt MₐXᵦ dissolving in water: MₐXᵦ(s) ⇌ aM^n+(aq) + bX^m−(aq), the Ksp = [M^n+]^a × [X^m−]^b. A larger Ksp indicates greater solubility. Ksp is used to predict precipitation and to calculate the maximum concentration of ions before precipitation occurs.

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